Cut your shortcut

1 · Say how each one picks a route

Beginner

In this model, how does each walker choose a route?

It follows what attracts it nearby, like a scent It computes the cheapest route to its destination It walks at random

2 · Compute the shortcut angle

Pedestrians cut a shortcut when the paved path is at least 30% longer: fresh ground "costs" them 1.3 times the path. The critical angle θ for leaving a straight path satisfies cos θ = cost of the path / cost of fresh ground.

Intermediate

At what angle should desire paths leave the sidewalk?

About 50° About 40° About 30°

3 · Predict the network on hard ground

In one simulation, fresh ground costs 65 times more than trail, as in snow or dense vegetation. The trail budget is not low.

Expert

What kind of network do the walkers form?

A more sprawling network, with more trails Trails meeting at about 40° A leaner network whose trails meet almost at right angles

4 · Reread animal trails

Several studies found fewer animal trails in open areas than in dense woods, and concluded that animals use open areas less.

Expert

What other explanation does the model offer?

Ground that is costly to cross favours trails, even without more traffic Animals really do avoid open areas, as those studies said Trails fade faster in the woods

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